<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    .box{
        width: 850px;
        height: 220px;
        background-color: black;
        margin: 0 auto;
        overflow: hidden;
    }

    .box-item{
        width: 200px;
        height: 200px;
        background-color: red;
        float: left;
        margin: 10px 5px;
        transform: translateY(0);
        animation: myTranslateY .6s ease-in-out .3s;
    }
    .box .box-item:first-child{
        margin-left: 10px;
    }

    .item1{
        background: url("/src/img/transform/01.jpg") no-repeat center;
        background-size: cover;
    }

    .item2{
        background: url("/src/img/transform/02.jpg") no-repeat center;
        background-size: cover;
        animation-delay: .4s;
    }

    .item3{
        background: url("/src/img/transform/03.jpg") no-repeat center;
        background-size: cover;
        animation-delay: .5s;
    }

    .item4{
        background: url("/src/img/transform/04.jpg") no-repeat center;
        background-size: cover;
        animation-delay: .6s;
    }

    @keyframes myTranslateY {
        from{
            transform: translateY(220px);
        }
        to{
            transform: translateY(0px);
        }
    }
</style>

<body>
    <div class="box">
        <div class="box-item item1"></div>
        <div class="box-item item2"></div>
        <div class="box-item item3"></div>
        <div class="box-item item4"></div>
    </div>
</body>
</html>